Navigation Tree Options

I have a requirement to move a clunky and often-crashing web start application to a full "pure" web application (JSP/Javascript/HTML). Unfortunately, the users have gotten used to some of the features web start can offer that normal pure web applications cannot...such as a customized right-click options on a navigatino tree. I have summarized what I think my current options are for replacing the tree structure, but can anyone else think of any other options? I have seen a lot of posts on this...and you'd think by now there would be a good open-source solution that was easily customizable and cross-browser compatible.

Option A - Building a navigation tree that uses Javascript to expand/contract the folders. Similar to the trees built here. Pros - All data could be loaded to Javascript objects and when the user expands/contracts a tree it will not need to reload the page. Pure "web" solution. Cons - Cross-browser compatibility with Javascript is shaky. Would have to figure out another way to provide user with functionality they can currently accomplish from right-clicking (since you cannot customize the right click from javascript/html).

Option B - Building a navigation tree that is built using html tables and built from Java on the back end. Similar to the solution offered here. Pros - All data loaded on back end and put into session, so it does not need to be reloaded every page request. Pure "web" solution. Cons - Would have to figure out another way to provide user with functionality they can currently accomplish from right-clicking (since you cannot customize the right click from javascript/html).

Option C - Cheat a little on the "pure web" requirement and use an applet for just the tree portion of the application so that I can keep the right click customizations the users are used to. Pros - Still wouldn't need to download a huge Jar file like web start does to user's machines. Would allow them to keep their customized right-click functionality they love. Cons - Applets aren't a "pure" web solution. Sometimes they can be clunky to use.